West Thames Area Drought Statistics

The Environment Agency has published its monthly statistics for the West Thames Area showing rainfall at its lowest since records began.
(Picture: Thames Water)
The data, courtesy of the EA West Thames Team shows just how severe the situation is:
Summary – February 2012
February was another dry month with below average rainfall for West Thames Area. Rainfall has been below average in 12 of the 17 months since October 2012, resulting in the second driest corresponding October to February period since records began in 1920. Mean February river flows were exceptionally or notably low for the time of year at 14 of our 15 indicator sites and groundwater levels at the end of February were notably or exceptionally low at 9 of our 11 indicator sites.
On the 20th February the south east of England officially moved into drought status. Rainfall February was another dry month with 42% of the long-term average monthly rainfall. About half of this fell as snow on the 4th which melted gradually over three days. The five months from October to February had two-thirds of their usual rainfall making this the second consecutive winter with below average rainfall. The 17 months since October 2010 have been the second driest corresponding period for West Thames Area since records began in 1920; only 1922 was drier.
On the 20th February the south east of England officially moved into drought status.
Soil Moisture Deficit/Recharge
Significant soil moisture deficits remained in the Berkshire Downs, Chilterns, Ock and Thame catchments at the end of February. This is very unusual for the time of year, when winter rainfall has usually wetted up the soil, allowing groundwater recharge. The dry soils mean that effective rainfall from October to February was just 17% of the long term average for this period. This is compounding the effects of last winter, when the six months from October to March saw only 51% of the usual winter recharge.
River Flows Mean monthly river flows in February were notably low at seven of our indicator sites, exceptionally low at another seven and below normal at one, the River Wye. On most rivers, status deteriorated from January to February, most notably on the River Wey and the River Loddon, where flows had previously been sustained by slightly higher rainfall and groundwater levels.
The lowest mean February flow since 1976 was recorded on two groundwater-fed rivers – the River Coln at Bibury and the River Kennet at Theale – and on two rivers dependent on regular rainfall – the River Cherwell at Banbury and the River Evenlode at Cassington.
Groundwater Levels
Groundwater levels in the Chalk at the end of February were notably low at three sites (Rockley, Gibbet Cottages and Tile Barn Farm) and exceptionally low at Stonor Park where the level was below the current detection limit. In the Oolitic limestone of the Cotswolds, the groundwater level was below normal at Ampney Crucis and exceptionally low at Jackaments Bottom and Fringford.
The full report is available here as a PDF
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